1. Field of the Invention
The present invention is related to an integrated system, and more particularly to an integrated system using a substrate module having an embedded phase-locked loop, and a fabricating method thereof.
2. Description of Related Art
Reference oscillation signals are the bases of digital logic operation. Although the frequency of the output signal of crystal oscillator has a better stability than LC oscillator, the frequency thereof is harder to alter. The oscillation circuit manufactured by using phase-locked loop has the advantages of wide oscillation frequency range and highly stable frequency, so that it is adopted by many electronic systems.
Please refer to FIG. 1, which is a schematic view showing the system architecture of a typical phase-locked loop. As shown, the phase-locked loop 10 includes a base frequency oscillator 101, a phase frequency comparator 103, a voltage controlled oscillator 105 and a loop filter 107. The base frequency oscillator 101 outputs an oscillation signal with frequency fr, and the voltage controlled oscillator 105 outputs an oscillation signal with frequency fo. Then, the phase frequency comparator 103 compares fr with fo for outputting an error signal PD which represents the magnitude relationship of fr and fo by positive/negative pulse. Then, the loop filter 107 converts the error signal PD into DC voltage signal Vr for outputting to control the output frequency fo of the voltage controlled oscillator 105, thereby the feedback architecture can control fo and fr to be identical. Therefore, the output frequency of the voltage controlled oscillator 105 and the base frequency oscillator 101 are synchronously stable.
Through utilizing frequency divider to alter the parameters of the feedback path of the phase-locked loop, all kinds of output frequencies can be obtained for be applied as clock generator in computer system. In communication system, the frequency synthesizer mounted at the front end of various wired and wireless transceiver devices also utilizes the phase-locked loop to produce accurate local oscillation frequency signal, so as to achieve frequency up conversion and down conversion of the RF signal. Besides, many control systems (such as, a CD-ROM drive control system) also utilize the phase-locked loop technology to achieve precise control. Therefore, phase-locked loop gradually becomes an essential for many electronic systems.
Owing to the technical improvement and also the combination of semiconductor manufacturing technology, chip scale package technology and PCB forming technology, the electronic system can be integrated as a miniaturized module product for being one of the components of backend product, so that it can be directly mounted on the circuit board, thereby reducing the design complicity of backend products. Besides, for cooperating with multi-function integration and miniaturization of electronic products, the module products also have the need in integration and miniaturization. Take RF module as example. The current development thereof is namely to integrate multiple communication systems, or integrate the communication system and the application system in one single module. However, owing to the integration, the circuit inside the module must be increased.
In view that the circuit and components of phase-locked loop always occupy a certain construction area and only leave limited area for other usage, which might increase the difficulty in integration, the applicant provides the present invention for improving thereof.